Hemophagocytic lymphohistiocytosis with a leukemoid reaction in an infant with scrub typhus.

A two-month-old male infant presented with a clinical picture suggestive of fever without focus. Treatment was initiated with broad spectrum intravenous antibiotics. The infant subsequently developed septic shock, hepatosplenomegaly and tachypnoea with oxygen dependency. There was laboratory evidence of anemia, thrombocytopenia and a leukemoid reaction. Infection induced hemophagocytic lymphohistiocytosis with a leukemoid reaction was suspected because of fever, splenomegaly and bicytopenia in conjunction with elevated serum triglycerides and ferritin. Empiric therapy with doxycycline caused a rapid resolution of the fever, and the diagnosis of scrub typhus was confirmed by a positive scrub IgM ELISA. HLH with a leukemoid reaction secondary to scrub typhus has not previously been reported in early infancy.